I should also have added that i have a pair of JBL 510s as well, and one of them rattles really badly, took them in for service and they use glue to fix the some internal problem. Still rattles so i cut back on bass boost which helps.
Whilst the 515xt were relatively new i traded them for the HK Elements. Different price range so i cant compare.
Like Donny also suggest the Yamaha DXR series is worth considering too, the price is still not as good as the special on the JBLs, but the full range sound, power and built quality is unbelievable. Ive just added a DXS12 sub to go with the pair of DXR10s and.. Very nice..
I understand there are always bad apples but since ive experienced both same problems on different size JBLs, i can only give feedback, as others have done to help me with most of my purchases.
Btw, if only the price back then were the same as the ones you spotted Bill, then ill probably wont have much to complain about, its just that hitting one or two lower piano keys and hearing them rattle is rather annoying.. But do audition them first if you have have chance. This review is just a hint to what to look out for and yes the price is very good.
Regards
Ky